The heritability of multiple mating in female Gryllus integer crickets
was studied. Two preliminary experiments were conducted to determine when
females first mate following the post-imaginal moult and to ascertain
whether constant exposure to males affects female mating rate. Female Q.
integer first mated at an average age of 3.6 days (S.D. = 2.3, Range = 0-8
days) . Exposing female crickets to courting males 24 hr daily did not
significantly alter mating rates from those females in contact with males
for only 5 hr per day.
A heritability value of 0.690 ± 0.283 was calculated for multiple
mating behavior in female Q. integer using a parent-offspring regression
approach. Parental females mated between land 30 times (x 9.8,
S . D. = 6. 6 ) and offspring matings ranged from 0 to 26 times (x 7 .3,
S.D. = 3.4).
Multiple mating is probably a sexually selected trait which functions
as a mechanism of female choice and increases reproductive success through
increased offspring production. Classical theory suggests that traits
intimately related with fitness should exhibit negligible heritable
variation. However, this study has shown that multiple mating, a trait
closely linked with reproductive fitness, exhibits substantial heritability.
These results are in concordance with a growing body of empirical evidence
suggesting many fitness traits in natural populations demonstrate heritabilities
far removed from zero. Various mechanisms which may maintain
heritable variation for female multiple mating in wild, outbred Q. integer
populations are discussed.